Seals for bearing arrangements are used to prevent solid contaminants and moisture from penetrating into the bearing while at the same time retaining the lubricant within the bearing or bearing arrangement. Bearing seals generally provide a minimum of friction and cause a minimum of wear while maintaining their efficiency even under the most unfavorable conditions so that bearing performance and life are not adversely affected.
Bearings can be provided with seals which are made integral with the bearing and seals which are positioned external to the bearing. Seals that are integral with the bearing are delivered in a ready sealed and lubricated condition from the manufacturer and are generally well suited for preventing penetration of contaminants from the outside in common environments.
Many factors have to be considered when choosing the right type of seal. These factors include the type of lubrication, the peripheral speed at the sealing surface, the horizontal or vertical shaft arrangement, the available space, the friction in the seal, cost and other considerations.
As mentioned above, bearing seals are commonly used to protect bearings mounted on shafts against the infiltration of dirt and water, and are particularly used in heavy environments, such as agricultural applications, heavy industries, etc. Such seals can take a variety of forms. One main type is a sliding seal which includes a sealing body of resilient material that is affixed to one of the bearing rings and at the free end has at least one sealing lip slidingly contacting the other bearing ring or a member attached to the other bearing ring. This type of seal is provided as an integral seal or as an external seal.
Another main type of seal, often used as an external seal, includes a first body connected to the rotating bearing ring and a second body connected to the stationary bearing ring. The two bodies form together a labyrinth seal designed to prevent the penetration of contaminants, moisture and lubricant. Bearing seals that are a combination of sliding seals and labyrinth seals are also used.
Depending on the construction of the seal, the resilient member can be made as a one part element, a two part element or an element made of more than two parts. A common feature is the resilient sealing lip that faces a cooperating sealing surface and in many cases is urged against the cooperating sealing surface by way of an annular spring.
Different sealing arrangements are known from EP-A1-0 241 581, EP-A2-0 519 654, and U.S. Pat. No. 5,024,449. These documents show different types of seals attached to roller bearings and ball bearings.
In environments or situations involving extraordinary quantities of contaminants, such as for example bearings used in agricultural equipment, it is preferred to utilize a particular externally mounted seal. When mounted at the manufacturer of the implement to which the bearing is associated, a knowledgeable and trained individual will typically be available to correctly mount and seal the bearing so that the bearing correctly operates to prevent external contaminants from entering the bearing. However, when it is necessary to replace these bearings, the replacement typically takes place in the field and so is not always performed by an experienced individual. There is thus the risk that the seal will be incorrectly applied, possibly leading to undue contamination of the bearing interior, and leakage or destruction of the lubricating properties. The ultimate result may be a breakdown of the bearing.
In light of the foregoing, a need exists for a bearing seal that is not susceptible to the same disadvantages and drawbacks as other known bearing seals.
It would be desirable to provide a bearing and seal combination which can be mounted and handled as a unit.
It would also be desirable to make it possible to externally secure a bearing seal to a bearing in a detachable manner and to improve the sealing properties of the bearing seal.
It would be further desirable to make it possible to provide a seal and bearing as one part at the time of primary manufacture while at the same time providing a design that facilitates replacing the seal in a simple way on after-market products when repair is necessary.